By James Rodgers
BBC News, Moscow
Who rules Russia?
Dmitry Medvedev (left) and Sergei Ivanov are seen as successors
It is a question which has always preoccupied Kremlin-watchers across the globe.
In Soviet times, they puzzled over photographs in Pravda to try to work out the Politburo's winners and losers.
In the years after the Soviet Union cracked and crumbled, they wondered whether Boris Yeltsin was actually running the country.
The real power, it was said, lay with the "family" - a clique made up of Mr Yeltsin's relatives and trusted Kremlin insiders.
Mr Yeltsin fought, and won, a battle with the parliament he had inherited from Communist times.
It began with a war of words and ended with tanks, troops and death on the streets of the Russian capital.
Leaving a gap
Vladimir Putin's time in office has been different.
Chechen separatists often quoted [Yeltsin's words] back at him as they fought the army he sent to crush them
"Stability" is spoken of with almost religious reverence. Mr Putin, who has presided over substantial economic growth, gets the credit.
Now Russia is wondering what comes next.
Despite petitions and pleas for him to stay on, Mr Putin has consistently said he will leave office when his second term comes to an end in March.
The Russian constitution does not permit a president to serve more than two terms of four years. If that changes, it is unlikely to be before March.
Many close to the centre of power here are currently stressing that "two terms" means "two consecutive terms". In other words, Mr Putin might still return.
Mr Putin's Russia is rooted in Yeltsin's in the sense that the country has striven not to repeat the mistakes of the 1990s.
Boris Yeltsin famously said to Russia's regions "Take as much sovereignty as you want!"
It was a phrase which later haunted him. Chechen separatists often quoted it back at him as they fought the army he sent to crush them.
Breakaway areas have been brought to heel.
As a precaution, there are no longer elections for regional governors. They are nominated by the Kremlin. Then the regional legislature has to decide whether to approve the candidate.
Brought to heel
They almost invariably do. That is another big change from the Yeltsin era. Where parliamentarians used to defy the president, they now trip over each other in the race to show their loyalty.
The opposition demonstrations in April... ended under the truncheons of the riot police...
A new opposition party was recently established.
"A Just Russia" says it will speak up for those who are not getting their share of the country's oil wealth but they have no plans to put up a candidate for the presidential election.
This is an "opposition" party which supports the president.
Mr Putin's critics accuse him of stifling democracy and the press.
During the Yeltsin years, there was a media explosion in Russia. The picture today is very different. Television remains by far the most influential news medium. All the major channels are either controlled by the state or businesses loyal to the Kremlin.
The main evening news bulletin has regained its Soviet era title, Vremya, and signature tune. Some would argue it has returned to Soviet-style editorial values, too.
Opposition to President Putin is small and poorly organised. It is also stifled. Demonstrations in April which ended under the truncheons of the riot police were the most recent example.
Garry Kasparov, the former world chess champion, organised one march.
He ended up being summoned for questioning by the FSB, Russia's secret police.
With Mr Putin - himself an ex-KGB officer - in the Kremlin, their power has grown.
Washington was swift to criticise the authorities' reaction. The State Department saw their response as "selective use of the law", in other words, political control of a judicial system which is nominally independent.
Whatever the West says, Mr Putin is genuinely popular.
Opinion polls suggest that he would easily win a third term if he were somehow able to stand.
Bowing to business
That is the true nature of the challenge which Russia's next president will face.
Mr Putin can claim support among ordinary Russians, the country's political and business elite, and foreign investors.
The two men most frequently spoken of as likely successors can enjoy influence in some of those areas.
Dmitry Medvedev holds the rank of first deputy prime minister. He is also chairman of the Russian energy giant, Gazprom.
In Russia today, business and politics are hard to set apart.
Sergei Ivanov holds the same cabinet rank as Mr Medvedev. Like Mr Putin, he is a former KGB officer.
Russia has not developed in the direction many in the West expected when the Soviet Union collapsed.
But there are business ties worth billions of dollars. That would simply have been inconceivable in Cold War times. Europe is likely to rely increasingly on Russia for energy supplies.
So the question now is not simply "Who rules Russia?" but how they rule it.